It is worse than that. In one case, the Australian Police kept a site up for an entire year (the site is said to have had as many as million accounts, although account numbers often don't map precisely to actual people) to try to collect evidence on people.

A lot of these sites only tend to stay up for a year or two before they get shutdown or get skittish, so keeping it up for a year is very significant and aids in the proliferation of this content.

They also deliberately circulated quite a few relatively uncirculated images to try to gain their trust after they took over the site.